Diabetes in Canada: Facts and figures from a public health perspective

Chapter 4 – Reducing the risk of type 2 diabetes and its complications

Introduction

Type 2 diabetes is caused by a combination of genetic, behavioural and environmental factors.
Although no cure exists, there is growing evidence that type 2 diabetes and its complications can
be prevented through the reduction of key risk factors. Currently, all the risk factors for type 1
diabetes are not well known, but researchers believe that interactions between genetic and
environmental factors are involved (Chapter 5).1

Risk factors for type 2 diabetes can be classified as modifiable and non-modifiable. Modifiable
risk factors are those that can be changed to reduce an individual's risk of developing type 2
diabetes and include unhealthy weight, physical inactivity, unhealthy eating, and smoking. Non-modifiable risk factors are individual characteristics, such as age, ethnicity, and family history of
the disease. Research aimed at better understanding the multiple causes and their interactions
continues. Understanding the distribution of risk factors within the population is useful for
predicting future trends in type 2 diabetes incidence and prevalence, as well as trends in diabetes
complications and mortality. It also provides information that can help in the planning of
prevention interventions.

Key modifiable risk factors for type 2 diabetes

Overweight and obesity

Overweight, and particularly obesity, is the most important risk factor for type 2 diabetes and its
complications. Excess body weight impairs the effectiveness of insulin use in the body, leading
to increased demand on the pancreas to produce insulin. This demand cannot be met indefinitely
and insulin production eventually declines, leading to type 2 diabetes. Overweight and obesity
also increase an individual's risk of other chronic diseases, such as cardiovascular disease,
arthritis, sleep and breathing disorders, depression, and some cancers.2;3

When the energy consumed through foods is not balanced by energy expended through physical
activity, unused calories are stored in the body as fat, which can accumulate in excess and results
in overweight and obesity (Box 4-1). However, the causes of overweight and obesity are
complex. Although unhealthy eating and physical inactivity contribute directly to weight gain,
many factors influence these behaviours, including individual, environmental, societal, and
cultural factors.

Box 4-1. Body mass index

The body mass index (BMI) is used to classify individuals as underweight, normal weight, overweight, or obese
in this report. The BMI is a unit of measurement that describes an individual's weight in relation to height, and is
calculated by dividing weight in kilograms by the square of the height in metres (kg/m2). The WHO and Health
Canada use standard categories to classify the BMI for adults aged 18 years and older (excluding pregnant
women):

Underweight

BMI <18.5 kg/m2

Normal weight

18.5≤ BMI <25.0 kg/m2

Overweight

25.0≤ BMI <30.0 kg/m2

Obese

BMI ≥30.0 kg/m2

Overweight and obesity by age

Among Canadians, the prevalence of self-reported obesity increases steadily through adulthood,
peaking in individuals aged 60 to 69 years and declining thereafter (Figure 4-1). In 2009-2010,
the prevalence of obesity in the 60 to 69 year age group was 22.5% for females and 22.6% for
males. Overall, males were significantly more likely to be overweight or obese than females at
every age. This difference was mostly due to the much higher proportion of males (40.6%) who
self-reported being overweight compared to females (27.2%), as the proportion of males who
self-reported being obese (19.5%) was comparatively similar to that of females (16.7%).

Figure 4-1. Prevalence† of self-reported overweight and obesity‡ among individuals aged 18 years and older, by age group and sex, Canada, 2009-2010

† 95% confidence intervals were based on a proportion that included both overweight and obesity.

‡ Overweight based on a BMI greater than or equal to 25.0 kg/m2 but less than 30.0 kg/m2; obesity based on a BMI greater than or equal to 30.0
kg/m2.

Source: Public Health Agency of Canada (2011); using 2009-2010 data from the Canadian Community Health Survey (Statistics Canada).

Overweight and obesity by province/territory

The geographic distribution of individuals who are overweight or obese is similar to the
geographic distribution of individuals with diagnosed diabetes (Chapter 1, Figure 1-2). In 2009-2010, the highest proportions of individuals with self-reported obesity were generally found in
the Atlantic provinces, Saskatchewan, Manitoba, and the Northwest Territories (Figure 4-2).

Figure 4-2. Age-standardized† prevalence of self-reported overweight and obesity‡ among individuals aged 18 years and older, by province/territory, Canada, 2009–2010

† Age-standardized to the 1991 Canadian population.

‡ Overweight and obesity based on a BMI greater than or equal to 25.0 kg/m2.

Source: Public Health Agency of Canada (2011); using 2009–2010 data from the Canadian Community Health Survey (Statistics Canada).

Overweight and obesity over time

Over the last 30 years, there have been significant increases in the rates of overweight and
obesity in the Canadian population, including children and youth. The proportion of adolescents
aged 12 to 17 years shown to be obese by physical measurements tripled from 3% in 1978 to
9.4% in 2004.4 Overweight and obesity in adolescence often persists into adulthood,5-8 placing
these individuals at risk of type 2 diabetes and other chronic diseases.9;10 This increase in obesity
is likely contributing to the emergence of type 2 diabetes in youth, a disease that was previously
viewed as an adult-onset disease only (Chapter 5, Type 2 diabetes).

Both measured and self-reported obesity among the Canadian population aged 18 years and older
increased between 1978 and 2009-2010 (Figure 4-3). Based on self-reported weight and height,
18.1% of adults aged 18 years and older were obese in 2009-2010. However, self-reported
measures are known to underestimate the true prevalence of obesity, which can only be obtained
through physical measurements. In 2007-2009, based on measured height and weight, almost one
in four (23.9%) Canadian adults aged 18 years and older was obese.

Figure 4-3. Prevalence of obesity† (measured, self-reported, and estimated) among individuals aged 18 years
and older‡, Canada, 1978 to 2009-2010

† Based on a BMI greater than or equal to 30.0 kg/m2.

‡ Data from the 1989 Canadian Heart Health Survey were based on respondents aged 18 to 74 years.

Diabetes and overweight/obesity

Figure 4-4 shows the distribution of BMI for Canadian adults with and without diabetes. The
median BMI of 25 kg/m2 for Canadians without diabetes indicates that half of all Canadian adults
without diabetes are overweight or obese. The median BMI for Canadians with diabetes is four
units (kg/m2) higher, at 29 kg/m2. In this case, more than three quarters (75.6%) of Canadians
with diabetes are classified as overweight or obese.

At every age, the prevalence of diabetes is higher among individuals who are overweight or
obese (Figure 4-5). The association is more pronounced among females than males. Among
males aged 18 years and older, the prevalence of diabetes among overweight or obese
individuals is 2.6 times higher than those who are of normal weight (9.7% versus 3.8%), while
among females aged 18 years and older the prevalence is nearly four times higher among
overweight or obese individuals than among those with normal weight (9.6% versus 2.6%).

Figure 4-5. Rate ratios of self-reported diabetes among individuals aged 18 years and older who were overweight and obese versus normal weight† , by age group and sex‡, Canada, 2009-2010

† Based on a BMI cut-off of 25 kg/m2.

‡ Marginal variance estimates for data in age groups less than 60-69 years; data should be interpreted with caution.

Source: Public Health Agency of Canada (2011); using 2009-2010 data from the Canadian Community Health Survey (Statistics Canada).

To obtain health benefits, the Canadian Physical Activity Guidelines recommend that children
and youth aged five to 17 years practice at least 60 minutes of physical activity (moderate to
vigorous intensity) per day; adults should practice at least 150 minutes of aerobic physical
activity (moderate to vigorous intensity) in total per week.15 Physical activity recommendations
for individuals with diabetes are presented in the Canadian Diabetes Association clinical practice
guidelines.16

Given its importance for preventing and managing type 2 diabetes, understanding the barriers to
physical activity among Canadians is essential to the development of interventions to encourage
regular physical activity. The 2007 Physical Activity Monitor17 identified the most frequently
reported barriers to physical activity for adults in the general population as:

Lack of time (72%);

Lack of energy, or fatigue (64%);

Lack of interest or motivation (62%);

Long-term illness, injury or disability (60%);

Cost (41%);

Feeling ill at ease or uncomfortable (40%);

Fear of injury (34%); and

Lack of physical skill (34%).

The barriers to children's physical activity, as reported by parents, were different from those of
adults. Safety concerns – such as too much traffic, poorly maintained sidewalks and bike lanes, and
poor lighting – ranked highest while perception of a child's lack of skill for doing physical activity
ranked lowest.

Physical inactivity by age

In 2009-2010, almost half (45.2%) of Canadians aged 12 years and older reported that they were
inactive (leisure and transportation index)i. Although youth (aged 12 to 19 years) were more
active than adults, almost a quarter (24.0%) were physically inactive. A higher proportion of
females aged 12 to 19 (28.6%) than males aged 12 to 19 (19.4%) were physically inactive.
Physical activity decreased with advancing age, and females were more inactive than males
across all age groups (Figure 4-6).

Figure 4-6. Prevalence of self-reported physical inactivity† among individuals aged 12 years and older, by age
group and sex, Canada, 2009-2010

† Based on a leisure and transportation index measure.

Source: Public Health Agency of Canada (2011); using 2009-2010 data from the Canadian Community Health Survey (Statistics Canada).

Physical inactivity by province/territory

The geographical distribution of physical inactivity was similar to that of obesity, with the
proportion of the population reporting physical inactivity (leisure and transportation index)
generally increasing from west to east and higher in the Northwest Territories and Nunavut
(Figure 4-7).

Unhealthy eating

Healthy weights depend on the balance of calories consumed with energy expended. Unhealthy
food choices can increase the risk of diabetes, particularly when over-consumption results in
overweight or obesity. Conversely, healthy eating can play an important role in the prevention of
many chronic diseases. Consumption of vegetables and fruit, nuts, legumes, fish/seafood, whole
grains, poultry, low-fat dairy products are all part of a healthy diet, as defined within Eating well
with Canada's Food Guide.18 Soluble fibre, found in foods such as citrus fruits, berries,
legumes, oats, and brown rice, helps to regulate glycemia.19 Foods that are rich in fibre can help
to control weight and may reduce the risk of type 2 diabetes. Fibre also lowers total blood
cholesterol and protects against heart disease.20 Some evidence suggests that a lack of vitamin D
hinders insulin function and glycemic control, and is a potential risk factor of type 1 and type 2
diabetes.21;22

Negative food choices include excessive alcohol consumption and consumption of processed
foods. A recent study implicates red meat as a risk factor for type 2 diabetes. After controlling
for other lifestyle and dietary factors as well as age and BMI, daily consumption of unprocessed
red meat increased risk of diabetes by 19%, while processed red meat increased risk by 51%.23
Consumption of fat should be limited to less than 35% of total calories consumed.24 Although
daily fat intake represented 31% of caloric intake in 2004, Canadians still exceeded the upper
limit for fat intake because overall caloric intake remained above recommended levels. The 31 to
50 year age group had the largest proportion of males (27%) and females (28%) who consumed
excess fat. The main sources of fat for adults were from the "meat and alternatives" food group,
followed by the "other foods" category, which included salad dressings, butter, margarine, and
vegetable oils.24 The combination of diabetes and hyperlipidemia can increase the risk of
cardiovascular disease and kidney disease.

Awareness of the connections between nutrition and health (nutritional knowledge);

Perceptions of healthy eating based on current dietary guidance, importance given to
freshness, unprocessed and homemade foods, and cultural/traditional meanings attached
to foods and health;

Exposure to media advertising or vendors promoting and selling individual products that
tend to be high in energy and low in nutrients; and

Lower socio-economic status and social inequity, which have been linked to poorer diet
and nutritional status and have led to community initiatives such as food policy
councils.25

Inadequate daily consumption of vegetables and fruit is used as a proxy measure of unhealthy
diet. A criticism of this measure is its use of an outdated recommendation of at least five servings
daily, which has now been increased to seven to eight servings daily. Further, the CCHS did not
examine the quantity consumed, but only indicated the number of times vegetables or fruit are
consumed. However, this indicator has been found to be an acceptable proxy for healthy eating
habits due to its correlation to the Health eating index.26 A diet that includes vegetables and fruit
may help prevent obesity. Also, low frequency of vegetable and fruit consumption is associated
with other lifestyle risk factors such as physical inactivity, tobacco smoking, and obesity.27

Unhealthy eating by age

Age-standardized rates of vegetable and fruit consumption indicated a marginal improvement
over time. Between 2003 and 2010, 58.7% to 56.4% of Canadians did not eat enough vegetables
and fruit. Males consistently consumed less vegetables and fruit compared to females.28 More
importantly, in 2009-2010, more than half of Canadians aged 12 years and older (55.9%) were
still reporting eating less than the recommended five servings of vegetables and fruit a day.
Compared to males, a greater proportion of females aged 12 years and older met the
recommendations in every age group, but still almost half (49.5%) did not meet the
recommendations. Almost two-thirds (62.6%) of males aged 12 years and older did not meet the
recommendations (Figure 4-8).

Figure 4-8. Prevalence of self-reported inadequate vegetable and fruit consumption†among individuals aged
12 years and older, by age group and sex, Canada, 2009-2010

† Based on a vegetable and fruit consumption of less than five times per day.

Source: Public Health Agency of Canada (2011); using 2009-2010 data from the Canadian Community Health Survey (Statistics Canada).

Unhealthy eating by province/territory

Rates of inadequate vegetable and fruit consumption vary across the country with the highest
rates in Newfoundland and Labrador, Nunavut, and the Northwest Territories. The scarcity of
fresh vegetables and fruit and the dietary patterns of the Aboriginal population may explain
lower consumption rates in the northern areas (Figure 4-9).

Tobacco smoking

Cigarette smoking can increase glycemic levels, impair insulin sensitivity, and promote
abdominal obesity,29 and has been associated with an increased risk of type 2 diabetes.30;31 The
combination of diabetes and cigarette smoking can increase the risk of some of the most serious
complications of diabetes: cardiovascular disease, kidney disease, and neuropathy.32 Thus,
smoking cessation is a key element of type 2 diabetes prevention and management.16

Tobacco smoking by province/territory

The Canadian Tobacco Use Monitoring Survey (CTUMS) is a Health Canada survey specific to
the surveillance of tobacco smoking in Canada. Based on CTUMS data, in 2009, 13.6% of
Canadians aged 15 years and older were daily tobacco smokers (12.1% of females; 15.1% of
males). However, because CTUMS currently does not survey the territories, all subsequent
statistics on tobacco smoking in this report are based on CCHS data.

Based on the CCHS, the proportion of individuals who smoked daily varied by
province/territory. In 2009-2010, the lowest rates of smoking among individuals aged 18 years
and older was reported in British Columbia, Ontario, and Manitoba. The rates of daily tobacco
smoking were below 24% in all provinces, while in the territories the rates were all above 30%
(Figure 4-10).

Tobacco smoking over time

Rates of smoking have been declining in Canada, although the decline was more pronounced for
females when compared to males (Figure 4-11). Based on age-standardized CCHS data, in 2010
15.5% of Canadians aged 12 years and older were daily tobacco smokers (13.0% of females;
18.1% of males).

Populations at risk for type 2 diabetes

Individuals with pre-diabetes

Pre-diabetes is a state in which an individual's fasting glycemic levels and/or response to a
fasting glucose tolerance test are higher than normal, but not high enough for a diagnosis of
diabetes. Pre-diabetes is diagnosed if IFG, measured by a fasting plasma glucose (FPG) test, is
between 6.1 mmol/L and 6.9 mmol/L or if IGT, measured by a oral glucose tolerance test
(OGTT), is between 7.8 mmol/L and 11.0 mmol/L.16 An individual may have pre-diabetes
without knowing it because it is asymptomatic and can only be detected through specific blood
tests.

Individuals with pre-diabetes are five to ten times more likely to progress to type 2 diabetes than
those with normal glycemic levels,33 and are also at an increased risk of cardiovascular disease.
Only 3% to 5% of individuals with normal glycemic levels will typically develop type 2 diabetes
over eight to ten years, whereas 30% of pre-diabetes cases with either IFG or IGT will develop
the disease. For high-risk pre-diabetes cases involving both IFG and IGT, the conversion rate is
60% — 20 times higher than among individuals with normal glycemic levels.34 These
individuals can benefit most from early detection and intervention to prevent or delay the onset
of type 2 diabetes and its complications.

It is estimated that pre-diabetes affects roughly 5.0 million Canadians over the age of 20 years.
This number is expected to grow significantly over the next decade — to 6.3 million Canadians
by 2016, according to some estimates.35 Among those aged 40 to 74 years, the prevalence is
expected to increase by 43.3%, from about 3.0 million in 2004 to 4.3 million in 2016. The
forecast increases are largely due to the aging of the population, the growth in obesity, and the
increase in non-white ethnicity.

Individuals with metabolic syndrome

Researchers have identified a set of conditions that often occur together and greatly increase the
risk of type 2 diabetes and cardiovascular disease.36 This constellation of risk factors is known as
the metabolic syndrome (Box 4-2).

Box 4-2. Clinical criteria for the diagnosis of metabolic syndrome

The presence of three or more of these risk factors indicates a diagnosis of metabolic syndrome:

† Drug treatment to control elevated triglycerides, HDL, blood pressure, and plasma glucose can also be considered
as an alternate indicator for these risk factors.

Source: Public Health Agency of Canada (2011); adapted from Alberti KG, Eckel RH, Grundy SM, et al.
Harmonizing the metabolic syndrome: a joint interim statement of the International Diabetes Federation Task Force
on Epidemiology and Prevention; National Heart, Lung, and Blood Institute; American Heart Association; World
Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity.
Circulation 2009;120:1640-1645.

Elevated waist circumference

≥102 cm in males; ≥88 cm in females

Elevated triglycerides†

≥1.7 mmol/L

Reduced high-density lipoprotein (HDL) cholesterol†

<1.0 mmol/L in males; <1.3 mmol/L in females

Elevated blood pressure†

systolic ≥130 mmHg and/or diastolic ≥85 mmHg

Elevated fasting plasma glucose†

≥5.6 mmol/L

The risk factors for metabolic syndrome — age, family history, overweight or obesity, unhealthy
eating and physical inactivity — have been linked to both type 2 diabetes and cardiovascular
disease. It is important for individuals to recognize symptoms early and to undertake lifestyle
changes, including weight loss and physical activity, to reduce potential risks of both type 2
diabetes and cardiovascular disease. According to laboratory measures from the 2007-2009
CHMS, 15.2% of Canadians met the clinical criteria for metabolic syndromeii (Table 4-1).

Table 4-1. Proportion of exceeded cut points for metabolic syndrome among individuals aged 20 years and
older, by sex and measure, Canada, 2007-2009

Proportion (%) exceeding
cut point

Proportion (%) meeting
the criteria† for
metabolic syndrome

Females

Males

Total

Females

Males

Total

† Presents with at least three out of five risk factors.

Source: Public Health Agency of Canada (2011); using 2007-2009 data from the Canadian Health Measures Survey
(Statistics Canada).

Women with gestational diabetes

Several factors place females at increased risk of gestational diabetes: obesity, a history of
gestational diabetes, a history of abnormal glycemic metabolism, a family history of diabetes,
belonging to an ethnic group with a high prevalence of diabetes, and age (≥25 years).37

Females diagnosed with gestational diabetes are at an increased risk of pre-diabetes and type 2
diabetes in the first five to ten years following the birth of their baby.38;39 Females with a history
of gestational diabetes are advised to have a diabetes screening test (OGTT) within six months
following delivery and to be routinely screened for type 2 diabetes thereafter;16 however, the
actual rate of postpartum diabetes screening is low.40 Children of women with a history of
gestational diabetes are also at an increased risk of obesity and type 2 diabetes.41-44 Canadian
Diabetes Association guidelines recommend that all pregnant women should be screened for
gestational diabetes, and that females with multiple risk factors should be screened regularly
during the pregnancy.16 Females who have had gestational diabetes can reduce their risk of type
2 diabetes through close postpartum monitoring and maintenance of a healthy lifestyle.16

Individuals with a mental illness

Depression and schizophrenia are two mental illnesses that are more common among individuals
with diabetes than among those without diabetes.45-49 Some studies have identified schizophrenia
as a risk factor for type 2 diabetes.16;50-52 In 2005, 11.9 % of Canadians aged 18 years and older
with schizophrenia reported having diabetes, compared to 5.3% of those without schizophrenia.53

A number of medications used to treat schizophrenia may affect glycemic levels and cause or
exacerbate diabetes.54 The use of second generation atypical antipsychotics increases the risk of
diabetes in individuals with schizophrenia by 30% compared to those with diabetes on first
generation antipsychotics.55 Another large study also linked atypical antipsychotics with diabetes
risk in individuals with schizophrenia, but found that risk differed by type of drug. Olanzapine
and clozapine were implicated with the highest risk for diabetes, while aripiprazole, risperidone,
quetiapine and ziprasidone were associated with the lowest risk.56 The association between
schizophrenia and diabetes is multi-factorial and may also be related to behavioural risk factors
and living conditions. Individuals with schizophrenia have higher rates of tobacco smoking (and
are more likely to be nicotine dependent), poor diet and physical inactivity.54 Compared with
individuals without schizophrenia, individuals living with the disease are also more likely to
have a lower socioeconomic status and to complete less years of education, both of which are
known to increase the risk of obesity.48;52;57 Elevated hormone levels associated with
schizophrenia are known to increase appetite, lead to weight gain, and cause insulin resistance.

Depression is common in Canada, with one in eight Canadians (12.2%) reporting symptoms
consistent with depression at some point during their lifetime.57 Depression can also contribute to
type 2 diabetes, although it is still unclear what the causal relationship is between these two
conditions and whether the relationship may in fact be bi-directional (Chapter 2, Mental
illness).58;59 This may be an indirect relationship, as depression is associated with health
behaviours, including smoking, physical inactivity, and unhealthy eating, that can increase the
risk of type 2 diabetes. The side effects of medications and biological changes in the body have
also put individuals with depression at an increased risk of type 2 diabetes.46 For example, a
study using Saskatchewan health administrative data reported that individuals with newly
diagnosed depression treated concurrently with selective serotonin reuptake inhibitors and
tricyclic antidepressants were at almost twice the risk of type 2 diabetesiii compared to those
treated with tricyclic antidepressants alone.60

Key non-modifiable risk factors for type 2 diabetes

Ethnicity

Ethnicity has been associated with diabetes, where certain ethnic subpopulations in Canada have
higher rates of type 2 diabetes. The influence of ethnicity reflects both biological and
behavioural differences that influence diabetes risk. For instance, people of South Asian,
Hispanic American, Chinese, and African ancestry are at higher risk of developing type 2
diabetes than those of European descent, and if they do develop type 2 diabetes, it is at an earlier
age and with lower BMI values.11;61 Further, another incongruity was seen with BMI for non-Europeans, where BMI significantly underestimated the greater amount of visceral adipose tissue
seen in this group.62 Genome studies have also pointed to specific ethnic differences in genes that
increase risk for type 2 diabetes.63

Ethnicity has also been associated with certain behavioural risk factors for type 2 diabetes.
Compared to Caucasians, other race or ethnicities tended to have higher rates of physical
inactivity, but individuals of Filipino, Chinese, or South Asian descent were between 1.6 to 6.0
times less likely to be obese (Table 4-2). Inadequate consumption of vegetables and fruit was
higher among individuals of Chinese and Filipino descent compared to Caucasians, but was
generally high in all ethnicities (ranging from 56.0% to 65.5%). Caucasians tended to smoke
more than the other groups. Also, self-care behaviour such as home glucose testing or foot
examinations, may vary by ethnicity, which could impact the quality of life of those living with
diabetes.64

Immigration

Immigrants to Canada, most of who now originate from non-European countries, are known to
have higher rates of diabetes. Results from an Ontario population-based study showed that, after
controlling for age, immigration category, education, income and time since arrival, immigrants
from South Asia, Latin America and the Caribbean, and sub-Saharan Africa had an increased
risk of diabetes compared to immigrants from Western Europe and North America.65 In addition
to genetic susceptibility, there is evidence that recent immigrants tend to have lower incomes and
poorer access to health services than the general Canadian population.66 While the evidence on
this topic remains mixed,67;68 a Toronto study identified high rates of diabetes with these factors,
linking them by way of "high risk" built environments that included decreased access to walking
and cycling trails, parks, and recreation programs and poorer access to healthy food choices or
health education programs.69 This may make these populations more vulnerable to risk factors
for type 2 diabetes. On the other hand, immigrants who have lived in Canada for over 15 years
present higher proportions of type 2 diabetes than recent immigrants, implying a "negative
acculturation effect".70

Social and environmental factors influencing
overweight and obesity

The determinants of health

"Many factors combine together to affect the health of individuals and communities. Whether people are healthy
or not, is determined by their circumstances and environment. To a large extent, factors such as where we live,
the state of our environment, genetics, our income and education level, and our relationships with friends and
family all have considerable impacts on health, whereas the more commonly considered factors such as access
and use of health care services often have less of an impact."71

The maintenance of a healthy body weight, participation in physical activity, and healthy eating
are the primary goals of public health interventions aimed at preventing type 2 diabetes.
However, an individual's health and the ability to adopt such healthy behaviours are influenced
by many factors, including the social, environmental, cultural, and economic conditions in which
the individual lives (the "determinants of health"). These include income, education and literacy;
employment and working conditions; food security; environment and housing; early childhood
development; social support and connectedness; and access to health care. All have a significant
effect on the distribution of risk factors within a population and are, in effect, "the causes of the
causes."72 Consequently, to deal with individual health behaviours and choices, it is necessary to
consider the factors that shape them.73

Socio-demographic factors

Low socio-economic status (as gauged by level of income, education, and employment status),
rural residence and ethnicity have been found to be associated with diabetes, its complications,
and its risk factors. In 2009-2010, several type 2 diabetes risk factors, including physical
inactivity (leisure and transportation index), inadequate consumption of vegetables and fruit, and
daily smoking were more common among Canadians in the lowest income quintile than among
those in the highest income quintile (Table 4-3). Individuals with less education were also more
likely to have risk factors for type 2 diabetes than those with higher education (Table 4-4). The
association was less pronounced between urban-rural residence and the various risk factors
(Table 4-5).

Table 4-3. Prevalence of self-reported modifiable risk factors among individuals aged 20 years and older, by
income quintile, Canada, 2009-2010

Prevalence (%) by income quintile (95% confidence interval)

Low

Lower-middle

Middle

Upper-middle

High

† Based on a BMI greater than or equal to 30.0 kg/m2.

‡ Based on a leisure and transportation index measure.

§ Based on a vegetable and fruit consumption of less than five times per day.

Source: Public Health Agency of Canada (2011); using 2009-2010 data from the Canadian Community Health
Survey (Statistics Canada).

The built environment

Although individual and interpersonal factors such as attitudes and motivation may account in
part for levels of physical activity, physical activity is also directly affected by a number of
aspects of the built environment, such as urban sprawl74 and access to walking paths, trails and
sidewalks.75 Built environments that promote high-energy diets, decreased access to healthy food
stores, and sedentary lifestyles are known as obesogenic environments. In Canada, higher rates
of obesity have been found in rural populations than in urban populations.76;77 This may in part
be due to the reliance on vehicles for transportation to destinations because of the lack of
convenient destinations within walking distance. In contrast, supportive built environments can
play a facilitating role in encouraging physical activity.78 For example, communities with a
variety of destinations safely accessible by foot are associated with a higher prevalence of
walking to work.79 Research has also shown that individuals who can easily walk from home to
commercial areas have increased levels of physical activity and lower BMI.80

The built environment also plays a role in healthy eating, alongside health and social policies that
influence food marketing. Access to local shops, health-related stores, and supermarkets81 has
been associated with lower levels of obesity, while the reversed association has been observed
between access to fast food restaurants and obesity.82 The availability and accessibility of
affordable nutritious foods is a particular challenge in low-income communities and in remote or
northern communities, especially those inhabited primarily by Aboriginal populations, where
dietary choice is constrained by high transport costs and spoilage.25;83

Interventions for the prevention of type 2 diabetes

Interventions to prevent type 2 diabetes can focus on the individual or on the population as a
whole. A population approach examines and addresses the entire range of factors that affect
health and aims to reduce risk factors in the population as a whole. In contrast, the individual
approach focuses on identifying risk factors and promoting behavioural change. Interventions
can include programs that promote healthy eating, regular physical activity and the loss of excess
body weight. While not as effective as lifestyle changes for longer term prevention, some
medications can be taken in addition to lifestyle changes to manage pre-diabetes. Individual and
population approaches are complementary and are most effective when they are integrated.

Primary prevention at the individual and population level is critical. Reducing the prevalence of
obesity would reduce the risks of developing diabetes as well as many other chronic diseases.
Therefore, the population approach to reducing diabetes focuses on creating supportive
environments and communities that enable their residents to maintain an active lifestyle and
healthy eating habits. It requires collaboration across sectors (such as the food, recreation and
school sectors), multiple strategies coordinated at different levels, and sustained effort over time.
Examples of health promotion strategies include:

Increasing time for physical activity in the school curriculum;

Providing access to community recreational facilities;

Forming and supporting networks of community-based organizations and services
committed to improving nutrition or physical activity;

Instituting educational campaigns that enable people to read and understand food labels;

Teaching young people to cook nutritious, low-fat foods;

Providing training to staff and volunteers for the skills required to promote population
health; and

Mandating a local health service, such as a diabetes education centre, to work with local
community groups to promote walking clubs.84

Prevention and health promotion strategies should be tailored to the level of health literacy of the
target population in order to better address its needs. Health literacy is a person's ability to find,
understand and use written information to promote, maintain and improve their health and is
only partially attributed to education level. It differs from the basic ability to read or understand
numbers in that it involves other complex skills, such as keeping up with constantly changing
information on new diseases and health threats, identifying and resolving contradictory
information from various sources, and communicating with doctors, friends, and family about
diagnoses and treatment options.

Recognizing differing levels of health literacy in the population plays a role in understanding
how healthy attitudes are shaped and, in the context of prevention and health promotion, how
knowledge about diet, physical activity and other healthy behaviours can be shared. For example,
60% of Canadian adults do not have the literacy skills needed to adequately manage their health
or health-care needs. Seniors, immigrants and the unemployed generally have lower levels of
health literacy than the national average. Moreover, a link has been observed between health
literacy and diabetes, where health regions with higher than average health literacy scores had
lower rates of diabetes.85

Looking ahead

The causes of type 2 diabetes are multiple, interlinked, and complex. Therefore, a holistic
approach that addresses the social, economic, environmental, genetic and lifestyle factors
associated with type 2 diabetes is needed to prevent and mitigate the disease and its
complications. Overweight and obesity rates have been increasing over time; reversing the
course of this trend and addressing other modifiable risk factors will be a crucial step in limiting
the rise of diabetes (Chapter 1). Efforts to prevent and manage diabetes and its complications
will not only benefit affected or at-risk individuals and their families, but also the overall
Canadian economy by reducing the economic burden of this disease (Chapter 3, Economic costs
of diabetes).

The Government of Canada promotes the prevention and control of diabetes through a number of
initiatives. The Canadian Diabetes Strategy (CDS), a component of the federal government's
Integrated Strategy on Healthy Living and Chronic Disease, supports both the upstream
prevention of type 2 diabetes through healthy eating and physical activity, as well as the targeted
prevention of type 2 diabetes and its complications in high risk populations through early
detection and self-management. The Aboriginal Diabetes Initiative (ADI), renewed for five years
in 2010, supports the prevention and management of diabetes in First Nations and Inuit
communities, both on- and off-reserve (Chapter 6, The Aboriginal Diabetes Initiative). Both the
CDS and ADI support organizations that work with communities at high risk of developing type
2 diabetes and its complications by providing funding for the development and implementation
of diabetes prevention, early detection, and self-management programs to address the unique
needs of the populations they serve.

Canadian Council on Learning. Health literacy in Canada: A healthy understanding.
Ottawa, ON: Canadian Council on Learning; 2008.

This measure likely underestimates true daily energy expenditure since it does not capture energy expended in usual
daily activities, including work activities.

This analysis did not include drug treatments for elevated triglycerides, HDL, blood pressure, and plasma glucose
as alternate indicators for metabolic syndrome risk factors; thus, it likely underreports the true prevalence of
metabolic syndrome.